Affiliation:
1. Department of Oral Biology, University of Florida College of Dentistry , Gainesville, Florida, USA
2. Department of Restorative Dental Sciences, University of Florida College of Dentistry , Gainesville, Florida, USA
3. Department of Microbiology and Molecular Genetics, McGovern Medical School , Houston, Texas, USA
Abstract
ABSTRACT
Co-infection with
Streptococcus mutans
and
Candida albicans
is associated with dental caries, and their co-cultivation results in enhanced biofilm matrix production that contributes to increased virulence and caries risk. Moreover, the catalase-negative
S. mutans
demonstrates increased oxidative stress tolerance when co-cultivated in biofilms with
C. albicans,
a catalase-producing yeast. Here, we sought to obtain mechanistic insights into the increased H
2
O
2
tolerance of
S. mutans
when co-cultivated with clinical isolates of
Candida glabrata
,
Candida tropicalis,
and
C. albicans
. Additionally, the
C. albicans
SC5314 laboratory strain, its catalase mutant (SC5314
Δcat1
), and
S. mutans
UA159 and its glucosyltransferase B/C mutant (UA159
ΔgtfB/C
) were grown as single- and dual-species biofilms. Time-kill assays revealed that upon acute H
2
O
2
challenge, the survival rates of
S. mutans
in dual-species biofilms with the clinical isolates and
C. albicans
SC5314 were greater than when paired with SC5314
Δcat1
or as a single-species biofilm. Importantly, this protection was independent of glucan production through
S. mutans
GtfB/C. Transwell assays and treatment with H
2
O
2
-pre-stimulated
C. albicans
SC5314 supernatant revealed that this protection is contact-dependent. Biofilm stability assays with sublethal H
2
O
2
or peroxigenic
Streptococcus
A12 challenge resulted in biomass reduction of single-species
S. mutans
UA159 and dual-species with SC5314
Δcat1
biofilms compared to UA159 biofilms co-cultured with
C. albicans
SC5314.
S. mutans
oxidative stress genes were upregulated in single-species biofilms when exposed to H
2
O
2,
but not when
S. mutans
was co-cultivated with
C. albicans
SC5314. Here, we uncovered a novel, contact-dependent, synergistic interaction in which the catalase of
C. albicans
protects
S. mutans
against H
2
O
2
.
IMPORTANCE
It is well established that co-infection with the gram-positive caries-associated bacterium
Streptococcus mutans
and the yeast pathobiont
Candida albicans
results in aggressive forms of caries in humans and animal models. Together, these microorganisms form robust biofilms through enhanced production of extracellular polysaccharide matrix. Further, co-habitation in a biofilm community appears to enhance these microbes’ tolerance to environmental stressors. Here, we show that catalase produced by
C. albicans
protects
S. mutans
from H
2
O
2
stress in a biofilm matrix-independent manner. Our findings uncovered a novel synergistic trait between these two microorganisms that could be further exploited for dental caries prevention and control.
Funder
University of Florida College of Dentistry
American Association of Cariology
HHS | NIH | National Institute of Allergy and Infectious Diseases
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
1 articles.
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1. Editorial: Control of biofilms to control caries;Frontiers in Cellular and Infection Microbiology;2023-11-30